Piano action



May 10, 1949- B. F. MIEISSNER PIANO ACTION Filed D60. 7, 1944 DQZOUUQ b0.06 0 MO ND Q0 "OI-LOW 8301"?" IN V EN TOR. BENJAMIN FMESSNER.

Patented May 10, 1949 UNITED STATES LZATENT OFFICE which the speed ofrepetition for rapid playing is.

not affected by the means for suppressing the rebound'of the hammers.

In addition, the invention has for its object to simplify theconstruction and arrangement of the novel piano action.

Other objectswill appear from the description hereinafter, and thefeatures of novelty'will be pointed out in the claims.

In the accompanying drawings which illustrate air example of theinvention without defining its limits,

Fig. 1 is an elevation illustrating the novel action;

Fig. 2 is a fragmentary enlarged view of the rebound suppression means;and

Fig; 3 is an oscillogram diagrammatically illustrating the operation ofthe novel piano action.

In the form illustrated in Fig. l, the reference numeral I indicates thekey bed which constitutesa part of the piano case in the conventionalmanner, and supports the key frame 2 on which thexkey '3 is pivotallymounted on the balance pin 4 and pad 5. A guide pin 6 and pad! areprovided inthe customary manner at the forward striking end 3-0. of thekey 3. At its rear end, the key 3 is continued in the form of adownwardly extending, preferably inclined, arm 3-b provided near itsfree end with an inserted plug 8 of*1ead or other metal to constitute aWeight atuthis point, said arm 3-b normally resting on a pad 9 suitablysecured in surface engagement with a rail in conveniently mounted in thecase of: the piano.

The. key is further provided with a capstan screwll projectingperpendicularly to the arm 3--b, anwcarried thereby at a predeterminedpoint-for co-operationrwith the hammer as will appear more fullyhereinafter. A screw-eye 12 or. equivalent device depends from the lower.end or the aunt-12 as illustrated'in Fig. 1.

The hammer comprisesa felt head l3 mounted -on-=.the-stem M which;in-turn'is carried .by'the.

butt i5 pivotally mounted at It, upon the flange ll. iasten-ed'by meansof, a screw I8 upon therail I9.- suitably mounted in the instrument. Thebutt. [5. is provided with a pad E5-a which is suitably secured to saidbutt l5,the latter further includ-" inga second pad 15-h located beneaththe pad. l5--a for the purpose of silencing noises which otherwise woulddevelop at this point. The rail. l9 carries a pad 20 located in the pathof movement'of. the key-arm -3-b and acting as a stop for the upwardmovement of the arm 3b when; the key 3 is operated. A hammer spring 2|is mounted on and'depends from a rail 22. suitably supported-inthe pianoand has its free end in; contact with the'butt I5 of the hammer asshown... A pad 23'is'suitab1y fixed in surface .engagementr.withtheqrail 22- to act as a stop for the damperas'willlmore fullyapp-ear hereinafter.

The-damper head 24 is attached by means of a set screw 25 to a damperrod 26 whichin turn is carried by. the .wooden damper lever 21influenced by a preferably wire. spring 28, and pivoted ata.29, :on aflange 38 which is attached to the rail LI 9. by means of; a screw 3 I.

The damper head is operated by the key 3 throughzthe medium of afloating link or push rod 33,rthreaded at its opposite ends, andcarrying; preferably-wooden buttons 34 provided with suitably-attachedfelt pads 35, and tubular noise;

silencing 'rubber' or other sleeves 36, as. illus-.

- 12' and '32,-and .the sleeves 36 located in the. in.

sides there0'f,;as illustrated. Screw-threaded adjustmentrof thewoodenbuttons 34 on the threaded. push=rod 33 serves to selectively adjust themotion;and:action-of the damper. The piano string 31 or other vibratormay be mounted in the instrument' in the conventional manner so as to becapable of being struck by the hammer l3,.and damped by the damper 24..

The hammer is provided with a guide rod 38 preferably of Duralumin,.andincludingahead 39 at its free end and a contiguous visco-elastic' padAll mounted on said rod 38,-in any convenient manner. This. Duraluminguide rod is prefer.- ably electroplated with a coating ofnon-oxidizing; metal" such aschromium to maintain low slidin frictiomforthe weight, M slidably mounted onthe. rod 33.,- which; also carries acompressionv spring daz'surrounding. said trod ea between the weight. Mand the harnmeiz'as illustrated in Figs. 1 and: 2.. In the-preferredarrangement, the. guide rod;

3 is set into a rubber bushing 43 countersunk into the wooden tail ofthe hammer, and secured therein any suitable manner, as by gluing, thearrangement being such that said bushing 43 projects outwardly beyondthe wooden tail of the hammer as shown.

The spring 42 is of a diameter at its hammer end to fit securely uponthe protruding end of the rubber bushing 43 and gradually increases indiameter toward its mid-section and then tapers to a smaller diameter ina direction toward the weight 4!. In other words, the spring 42 tapersin opposite directions from an enlarged midsection so that when saidspring 42 is fully compressed. its length is relatively small. Therighthand end of the spring 42 in Fig. 1, fits snugly about the guiderod 38 to prevent vbiratory noises, and at the same time, is arranged toslide freely along the guide rod 38 when struck by the weight 4|, in theoperation of the piano action.

The weight M preferably is provided with a noise-silencing leather orother bushing 4Ia impregnated with graphite as a lubricant, tofacilitate the sliding movements of said weight 4|, lengthwise of theguide rod 38. Preferably, a relatively thin rubber Washer 41 is alsolocated between the pad 4% and the weight 4i, to avoid and silenceslapping noises otherwise developed,

when the weight 4| strikes the pad 40. The latter, in its preferredform, consists of a visco-elastic synthetic material having highviscosity and low elasticity such as a synthetic resin having theseproperties. To prevent cold flow of this material, it may be dipped inliquid rubber to coat it with a thin film of rubber 4E-a, and when thisrubber film is dry, and the pad 4!] has been cemented or otherwisesecured to the head 39 of the guide rod 38, the entire pad 40 may bedipped in flake graphite, which is rubbed into the rubber to preventstickiness. For visco-elastic pads which develop no slapping noise whenimpacted by the weight 4|, the rubber washer 4'! may be omitted, and forpad material which is not subject to cold flow, the rubber film may alsobe omitted. Furthermore, for non-sticking pad material, the graphitecoating may be omitted,

The hammers normally rest against a pad 48 suitably mounted in surfaceengagement with a rail 49, which, by conventional means not shown, maybe shifted at will to the left in Fig. 1, so as to shorten the hammerstroke for soft-pedal operation. The pad 48 may also be made ofviscoelastic material to suppress rebound of the hammer from said padfor strong, quickly-released key blows. For such key blows, inconventional actions, the hammer, especially of the heavy, bass type, iscapable of rebounding back to the strin and re-striking the same, whichobjection is avoided by the use of the visco-elastic pad 48 instead ofthe customary felt.

The dampers 24 are also controlled by means of a conventional loud pedallifter, not shown, which, by pushing all of the damper rods at theirlower ends to the left, disengages all dampers from the strings 37,independently of the key control of said dampers.

In operation, when the key 3 is struck at its playing end 3a, thecapstan screw ll exerts a pushing force against the pad l5-a, to therebycause the hammer [3 to be moved toward the string 3 or other vibrator.The capstan screw l l remains in contact with the hammer until thelatter reaches a point about of an inch from its associated string 31,at which point the key 3 and its arm 3b come to rest against the padssix 4 1 and 20, respectively. At this stage, the hammer continues itsmovement onward under its own momentum, and strikes the string 31 orother vibrator, from which the hammer rebounds back into contact withthe capstan screw II through the pad i5-a.

The weight 41 is accelerated with the hammer, being driven by the pad 40and guide rod 38 carried by said hammer.

When the hammer head 13 strikes the string 31 or other vibrator, and thehammer begins to lose forward velocity, the weight 4| starts to slidelengthwise of the guide rod 38 toward the spring 42, and as the hammerrebounds in the reverse direction from the string 31 or other vibrator,the weight velocity on the guide rod 38 increases. As the hammer head I3 is about to leave the string 31 or other vibrator, the weight 4|begins to compress the spring 42, the amount of such compression varyingwith the force of the key blow.

As the spring 42 is thus compressed, it develops an opposing forceagainst the hammer which somewhat reduces the velocity of the hammertoward the capstan screw l I. Part of the kinetic energy of the weight4! is therefore utilized to slow down the velocity of the hammer as thelatter rebounds from the string 3! or other vibrator, and a part of saidenergy is stored in the spring 42 as potential energy.

The hammer continues onward in its return movement, strikes the capstanscrew I I (when the key 3 is held down) deflects the stem l4 andcompresses the pads 5, I5a, and [5-17. Then, as the hammer starts torebound back toward the string 37 or other vibrator, the weight M isdriven by the compressed spring 42 against the rubber washer andvisco-elastic pad 40 on the guide rod 38, with just the right amount offorce to neutralize the tendency of the hammer to rebound toward thestring 31.

I have found that, with leather or felt pads at 5, l5a, and |5b, theweight of the element 4| should be 0.2 times the weight of theassociated hammer, as measured with the hammer stem 14 horizontal andthe hammer flange ll fixed, as in a vise.

The oscillogram illustrated in Fig, 3 shows diagrammatically, the hammermotion with the instant improved and novel anti-rebound attachment.

The hammer leaves its normal position of rest on the pad 48 of the backrail 49, as the key 3 is struck, and gains velocity until the drivingmotion of the key 3 is stopped by the pads 1 and 22 when the curvecrosses the line A. Thereafter, the hammer continues its motion until itstrikes the string 31 or other vibrator where the curve crosses the lineB. The hammer then slows down, comes to a stop at C, and reverses itsdirection of movement back to the capstan screw I I, which it recontactsas the curve recrosses the line A. When the key 3 is held down followingthe key blow, the capstan screw 1 l remains in fixed positioncorresponding to the line A of the hammer curve. The hammer, therefore,strikes the capstan screw l I through the intervening pad l5-a, and, dueto eompliances in the hammer stem 14, pads I5-a, [5-11, and 5, andelsewhere in the key assembly, the hammer deflects back to the point Din the curve, after which it again reverses its motion toward the string31 or other vibrator. Just as the hammer is about to leave the capstanscrew II at point F of the curve, the weight 4|, impelled by the spring42, strikes the rubber W-G'Shfirll and pad 401,, and thereby brings thehanmrento-rmtupm andiiniengagement with the eapstamscnew It.

Iir teaseswhere: the key 3 i is not: held. down: following: thakey blow,as in rapid-repetition, the hammer continues on backward from the-string31: on other vibraton. along the dotted line until itrecontactsthercapstan screw i l' Or the pad on therback raiiiMInithis'cas-ei. the weight M strikes the pad 40 while: the hammer movinginthe direction, and thus somewhat accelleratesthe return motion oi saidhammer back: to its normal position: In thismannenthespeed ct repetitionof the: hammer is unimpaired by the anti-rebound attachment ot theguiderrod' and weight assembly.

The operation" of: the anti-reboundmeansis effective at allhammervelocities due tot-he fact that'the spring '4"2-1feg-u12testheieffective'forward and rearwardi stroke oiv the Weight 4!. Thisstroke oir'tra-vel distance, islargest for high ham mer' velocities andsmallest for lowest hammer velocities; the velocityof the weight ilbeing equal to the: hammervelocity for all key blows ofevery strength;

The amount oft kinetic energyrequiredin the weight M to neutralize thekinetic energy ofthe hammer and bring. it.v to rest without reboundingback to the string 31 or other vibrator, is considerably lower than thatrequired to effect this operation in the manner disclosed in-mycopending application, Serial No. 556,166, filed September 28, 1944.This is due to the fact that con-- siderable of the residual kineticenergy in the hammer, after it leaves the string or other vibrator, isdissipated in the various compliances during its.- rearward deflection.after recontacting the capstan screw. The velocity of thehammer as'itbeg-insto leave the capstanscrew in areturn movement toward the string,is, therefore, considerably-lower than its velocity on leaving thestring. Since its kinetic energy is proportional to the square of itsvelocity, this reduction in its velocity before neutralization by theloose weight 4|, is important in reducing the amount and dimensions ofthis loose weight 429 necessary for efiicient operation.

The reduction in the velocity of the hammer at the point F of the curvein the oscillogram of Fig. 3, just before the weight M strikes the pad40, may be increased by choosing, for the pads l5a or l5b or fOr both ofthese on the hammer butt i5, suitable material having viscous dampingproperties which will still further absorb kinetic energy from thehammer. This makes possible a still further decrease in the weight ofthe mass 4!, required to prevent rebound of the hammer back towards thestring 3! or other vibrator.

In the same manner, the pad 5 beneath the key 3 on the balance rail pin4, may also be made of visco-elastic material since thi pad 5 iscompressed when the hammer strikes the capstan screw II. It will alsoassist in absorbing kinetic energy from the hammer so as to reduce theamount thereof requiring neutralization.

I have found that by the use of these viscoelastic pads at 5. l5a,, andIii-b, the hammer velocity is so much reduced as the hammer begins torebound from the capstan screw back to the string, that the weight ofthe loose mass represented by the weight 4!, may be reduced toapproximately 13% or less of the weight of the hammer with its stemhorizontal and its flange fixed in a support, as against a 21% weight ofloose. mass with" conventional leather and: ,felt pads. To;preventtcold? flow." of these-pads when the latter are'subject. to.such; fiow said; pads may be encasedin a thinrubberskinor. film: bydip.- ping them in rubber, drying, and; covering with graphite. Ifthepads 5; l:5a,. and |.5-b are sufficiently eiiective to. absorb all. theresidual kinetic energy of the hammer for maximum strength or key blowso as to prevent. hammer. rebound from the capstan screw back to; thestring, the anti-rebound attachments 38, 39, 40', t-i, 22,.andi 47maybeomitted- I have foundthat the guiderods 38" maybe of the samelength for all hammer sizes, and that the springs 32 may b'e'ot thesamersize and stiffness" for all hammer sizes. The purpose of, therubber bushing 43 is toprevent the shock impulse, set up by the Weight4| when striking the pad. dd, from being comm unicated. to the hammerhead !3 and through its stem. l4- and flangehl l into the structure otthe piano from which it radiatesas an. impact, noise- Although thepresent invention has; beendescribed in conjunction with a preferredembodiment, it is to be understood. that modifications and'variationsmayberesorted towithout departing from the. spirit and scope oi theinvention, as those-skilled-in the. art willreadily understand. Forinstance, the sliding or suppression weights may be replaced by loosemasses of granular, solid. or. liquid: type contained in a tubular partof or attachment to. the hammer; Such variations. and modificationsareconsidered to be with.- in the purview and scope of. the claims.

I claim:

1. In a musical instrument of the pianoty-pe, a vibrator, a hammermovably mountedinstriking relation to said vibrator, a movably mountedoperating key, actuating means operated by said key effective onv saidhammer to cause the latter to strike said. vibrator, a reboundsuppressing weight associated with saidzhamrner" and movable relativelythereto, and a spring co operating with said weightto reduce thevelocity of. the return movement-of the hammer from the vibrator, andtoneutralize rebound. of said hammer relatively to said actuating means.upon the return of the hammer thereto subsequently to its impact againstsaid vibrator.

2. In a musical instrument of the piano type, a vibrator, a hammermovably mounted in striking relation to said vibrator, a movably mountedoperating key, actuating means operated by said key effective on saidhammer to cause the latter to strike said vibrator, guide means carriedby said hammer and extending in the direction of its operativemovements, a rebound suppressing mass movable relatively to said guidemeans as said hammer is operated, and a spring acted on by said mass toreduce the velocity of the return movement of the hammer from thevibrator, and to neutralize rebound of said hammer relatively to saidactuating means upon the return of the hammer thereto subsequently toits impact against said vibrator.

3. In a musical instrument of the piano type, a vibrator, a hammermovably mounted in striking relation to said vibrator, a movably mountedoperating key, actuating means operated by said key efiective on saidhammer to cause the latter to strike said vibrator, a guide rod carriedby said hammer and extending in the direction of its operativemovements, and a rebound suppressing means including a weight slidablelengthwise of said rod for reducing th velocity of the return movementof the hammer from the vibrator, and for neutralizing rebound thereofrelatively to said actuating means upon the return of the hammer theretosubsequently to its impact against said vibrator.

4. In a musical instrument of the piano type, a vibrator, a hammermovably mounted in striking relation to said vibrator, a movably mountedoperating key, actuating means operated by said key efiective on saidhammer to cause the latter to strike said vibrator, a guide rod carriedby said hammer and extending in the direction of its operativemovements, a rebound suppressing weight externally carried by andslidably mounted on said rod, a head carried by said rod in the path ofmovement of said weight in one direction, and a rebound suppressingspring carried by said rod in the path of movement of said Weight in theopposite direction, and arranged to be coll pressed thereby to reducethe velocity of the return movement of the hammer from the vibrator, andto force said weight against said head to neutralize rebound of saidhammer rela ively to said actuating means subsequently to its impactagainst said vibrator.

5. In a musical instrument of the piano type, a pad of visco-eiastic,energy-absorbing material, and an elastic film encasing said pad andhaving sufiicient resiliency to allow said pad to deform under pressurand to restore said pad to its normal shape when the pressure isrelieved.

6. In a musical instrument of the piano type, a pad of visco-elastic,energy-absorbing material, and a rubber skin encasing said pad andhaving sufficient resiliency to allow said pad to deform under pressureand to restore said pad to its normal shape when the pressure isrelieved.

7. In a musical instrument of the piano type, a vibrator, a hammermovably mounted in striking relation to said vibrator, an operating keyin operative association with said hammer to cause the latter to strikesaid vibrator, a rail, and a pad of visco-elastic material on said railagainst which said hammer normally rests and to which it returnssubsequently to its impact against the vibrator, said pad suppressingrebound of said hammer therefrom subsequently to said return thereto.

8. In a musical instrument, an exciting action for a vibratorcomprising, in combination, a hammer movabl to strike the vibrator;actuating means for moving the hammer and against which the hammerrebounds after striking the vibrator; means, rendered effective by thestriking of the vibrator by the hammer, for storing kinetic energy inpotential-energy form during the rebound of the hammer from thevibrator; and means rende 'ing the stored energy effective to oppose arebound of the hammer from the actuating means.

9. In a musical instrument, an exciting action for a vibratorcomprising, in combination, a hammer movable to strike the vibrator;actuating means for moving the hammer and against which the hammerrebounds after striking the vibrator; a mass moved by said actuatingmeans coincidentally with the movement of the hammer by the actuatingmeans, and movable relative to the hammer; resilient means regulatingthe motion of said mass relative to the hammer upon the striking of thevibrator by the hammer; and means, forming a portion of the hammer,against which said mass delivers an impact when the hammer has reboundedagainst the actuating means.

BENJAMIN F. MIESSNER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,167,863 West Jan. 11, 19161.184181 Holden May 23, 1916 1,598,203 Laukandt Aug. 31, 1926 2,082,548Pape June 1, 1937 2,226,877 Schulze Dec. 31, 1.940 2,288,852 Socin July7, 1942 2,329,009 Socin Sept. 7, 1943 FOREIGN PATENTS Number CountryDate 206,732 Germany Feb. 10, 1909 530,257 Germany July 25, 1931

